Radio compass system



Nov. 10, 1931.

G. T. ROYDEN l,831,465

'RADIO COMPASS SYSTEM Filed Dc. 28', 1925 /4 /6 f /lz4 /Za /NVE/vrn Byeorge Z' @agde/7 M/w Q ArTaHHEY- Patented Nov. lO, 1931 UNITE@ STATt-.S

miem carica GEORGE '1". ROYIDEN, OF PALO ALTO, CALIFORNIA, ASSIGNORFEDERAL TELEGRAPH COMPANY, OF 'SAN FRANCISCO, CALIFORNIA, A CORPORATIONOF CALIFORNIA RADIO COMPASS SYSTEM Application led December 28, 1926.Serial No. 157,482.

This invention relates generally to radio signalling receiving systemsespecially applicable for locatingvthe direction of a signal source. Y 4f y 5 In radio compass installations, the receiving apparatus usuallyincludes a. rotatable loop antenna connected to a cascade amplifier vanddetector. Connected to the detector there is a translator Which mayeither consist of a 0 telephone receiver orone or more relays forcontrolling a visual or audible indicating device. Generally the systemis operated by rotating the loop until the signal response is of minimumstrength, the position of the loop 5 ythen indicating the direction ofthe signal source. In case of a translator employing relays, thiscondition may befindicated by a visual indicator such as a flashinglight. While arrangements of this sort give good D results, it ispossible that an inexperienced yoperator may obtain a false bearing dueto a cessation of signals from causes other than a critical position ofthe loop. For example, the signals may become Weak due to fading 5effects or because of the condition of the signal transmitter.

Itis an object of this invention to devise a radio compass system WhichWill prevent errors by providing means by Which an observer D may beassured of a proper critical position of the loop. v vIt is a furtherobject of this invention to devise a signalling system which Willindicate Athe nature of a signal being received by one 5 apparatus bythe combined effect of that apparatus and another receiving apparatusupon a common translator. Y

Further objects of this'invention will 4appear from the followingdescription in which 3 Ihave sert forth the preferred embodiment of myinvention. It is to be understood that the appended claims are to beaccorded a range ofelectrical and mechanical equivalents consistent withthe state of the prior art. In the central ligure of the drawing I haveshown a radio compass system incorporating the principles of thisinvention.v Such a system utilizes a directional radio -receivercomprising for example-a rotatable loop antenna r1() connected tosuitable receiving apparatus such as a radio frequency amplifier 11,detector 12 and audio frequency amplifier 13. The system is preferablymade selective by timing one or more stages of the radio frequencyamplifier 11. vFor purposes of illustration I have indicated aselectively tuned system'by showing a radio frequency transformer 14coupling together the loop antenna 10 and thev amplifier 11, thistransformer being tuned by means of 'a'variable condenser AssociatedWith the directive receiving apparatus described above, there isanon-directional receiver Which in a typical instance may comprise aradio frequency amplifier 17, detector 18 and audiov frequency amplifierY 'is adapted to be influencedby both of the receivers, indicates acritical adjustment of loop antenna 10 When both of the receivers'aretuned to the same signal. One suitable form of translator utilizes amirror galvanoineter 26 having its armature 27 connected to the outputof ampliner 13. A beam of light-from a .lamp 28 is focused upon themirror 29 of this galvanometer, and is reflected upon a l screen 31. Thelamp 28 is energized from a V local battery 32 through a circuitcontrolled by relay 33. The windings of this relay are connected to theamplifier 19 ofthe non-directional receiver sov as to be energized .fromthe received inthe directional receiver.

output of the last amplifier stage. The relay 33 is designed so that forthe ordinary audible signal frequency, its armature 34 will not flutterbut will be held against contact 36. The armature, however, is biased asby means of a spring 37 so that when no signals are being received bythe nondirectional receiver, armature 34 breaks the energizing circuitfor battery 3:2. For observing the position of the light beam, thescreen 3l is provided with a Window 3S, and another ,window 39 may beprovidedy for observing the condition of lam-p 28. Y

Vhen operating` the system as described above, both the directional andnon-directional" receivers are tuned to a certain transmitting stationor to a given source of radio signals. This may be accomplished by usingtelephone receivers inrplace of the translator, or the two receivingapparatuses may previously be adjusted sov that the operator may merelyoperate the-simultaneous control until lamp Q8 is lighted.l Thegalvanometer may then be `adjusted so that the beam of light striking'the mirror 29 will bev reflected along path L1 to illuminate the. window38. l`o secure a bearing indieatiom the loop is then` slowly rotated toa; position of minimum signal; strength. Thisis indicatedy to theobserver by darkening-'of Window 38 due Vto a deection ini thegalvanometer 'whichl changes the angle of reflection and; thus shiftsthe beam to path 4Q. By notingthat window 39 is illuminated when window38 is darkened, the operator may be assured that the bearing observationin the mirror is a true indica.- tion of a criticalv position; of theloop 10. It is obvious-that instead of having a window 38 darkentoindicate critical condition, the gaflvanometer 26' may be arrangedLto, deflect the beam tonormally darken the window and illuminate itwhen` the signal strengthr in the directional receiver is at a minimum.

It will be apparent that this system isk a decided improvement on radio'compass systems whichl utilize a singleV receiver.A The response of thetranslator which indicates a criticall position of the loop is notmerely due tov'theabse'nce of signal energy, but is due to the receptionof signal energy inthe one receiver when substantially no energy isvbeing Thus the response is more reliable inv that it is positive ratherthan negative. It is obvious that'V a dill'erentially wound relay, or asystem of interlocking' relays may be substituted for the galvanometerarrangement.

y l. In Va radio signaling system, two receiving apparatus, each'ha'vingan'independent antenna, a light source adapted to be illuminated byreception of signalenergy by oneapparatns, and'mejans controlled byv theother Aapparatus for-aliecting light rays fromy Ycontrolled by receivedsignal energy from the other apparatus for varying the visual indicatibnproduced by said lamp.

a. In a radio signaling system, two receiving apparatus each having anindependent antenna, indicating means including a lamp adaptedr to beilluminated by reception' of signal energy by one apparatus,- and' meanscontrolled by received signal energy IOm the other apparatus forvariably defiecting light f froml said lamp.

Y 5. In a radioy system,y a direction-V find-ing apparatus lincluding a.rotatablel directional antenna associated with: a radio detector,indicating means controlled by the output of said detector, and means`for preventinga false 'bearing indication comprising Aa nondirectionalreceiving apparatus includinglanother radio detectoxgnnd meanscorrelating said last detector withv saidindicating means forindependently indicatingV reception of a bearing signal by saidnon-directional apparatus.- y

.6. InV aV radio system.I a directionalfinding apparatus' including arotatable directional antenna associated with a radio dectector,`indicating means controlledby the output. of saidl detector, and means.for preventing a. tal-se bearing indication comprisingya nondirectionalreceiving apparatus includinganother radio detector, and means'correlating said last vdetector with Said indicatingmeans forindependently indicating' reception of a. bearing signal by said?nonLdirectional apparatus, said' lastV means serving to render saidiirst named indicating meansoper'ative in response to'receptioi'iofthe"directionsignal by said non-directional apparatus. n

7. In a radio compass, a receiving s tem having movable absorptionstructure, t e received energy varying with the amplitude of radiantenergy andthe position of said structure with respect to thewave-frontthereof, a second receiving system of the received energy of whichvaries solely with the amplitude of said radiant energy, an indica-torlassociated with said lirstgsystem responsive to the received energythereof for indicating ositi'on and means res onsive to the ener 5 P Y yof said second system controlling the operativeness of said indicator.

8. In a radio compass, a directional receiving system, an indicatorhaving a. deflecting member Whose position is determined by thedirection of propagation of energy received by said system, a secondreceiving system, and means responsive to energy received by said secondsystem controlling the ability of said defleeting member to produce anindication.

In testimony whereof, I have hereunto set my hand. y

GEORGE T. ROYDEN.

